So my girlfriend's car wouldn't start after work. 2007 Mazda3 s 2.3L sedan w/ 120k miles. It had been cranking slow lately and it is really cold. Battery, right? So we get a new battery, drive to her office 20 miles away, install battery...and nothing. Everything powers up, but no start. OK, so the battery came off the shelf a little under charged. We hook up the jumper cables to my truck and let it charge for a good 15 minutes. Still nothing. I plug in my OBDII reader and use Torque. 14V with the truck hooked up, 12.5V without. In any situation, the starter doesn't even try to engage. No clicking, no noises, nada. I heard some relays click under the hood, but that is the only sound made.
When I had a Mazda3 (with the 2.0l), it had corroded starter wiring. I couldn't get under the car tonight in the dark, snowy parking lot, so I couldn't check.
If all else fails, I'm going to have it towed back to her place so I can dig in deeper.
Any ideas? I'm all ears!
TIA!
Defiantly check the starter and everything going to it, it is possible the starter solinoid took a crap as well.
Good luck!
In reply to CGLockRacer:
Check to see if the starter is getting power on the signal wire... If it is, and the main power wire is good then you need a starter...
If there is no power, you'll need a wiring diagram to check out the starting circuit and figure out where power needs to come from...
Some idea's that come to mind, are possible bad relay, fuse or anti theft problem...
Sonic
SuperDork
1/22/13 9:01 p.m.
I agree, check the starter signal wire. It is a small wire that slides onto a spade terminal on the starter. It is a bit hard to get to from the top, but unless you have huge arms, you cam probably snake them in there. If there is 12v to that when the key is in position 3, then the starter is the culprit. If not, then work your way back: main fuses, clutch switch, etc.
ARGH!!!
Update. She got the car started and it is now in her garage. It sits for about 45 minutes. I start it and get it up on the ramps. Get the under cover off. Wiring looks clean. I have her try and bump the starter to check voltage....and it won't start again. I'm pulling my hair out on this one. I swapped the starter relay with the same type in the fuse box. No change.
When she was trying to start it, I did not read voltage on the bare copper wire or the small wire that go to the starter solenoid.
Any ideas? Thanks again!
It also won't start in Park or Neutral.
Tralfaz
New Reader
1/23/13 5:46 p.m.
This is a bit left field, but I had similar symptoms on an older car that had dirty/loose terminals. Everything worked fine (and the voltage read correct) except the starter as it was trying to pull amps.
Is there 12v to the solenoid signal wire (the small one) when it won't crank/start? If not maybe the ignition switch is going out. Try wiggling it and cussing while trying to start it.
No voltage on the small wire would indicate a bad ignition swith or the neutral/park switch
Try a hot wire to that terminal on the starter. Starter engages and turns engine, bad units as as above.
No starter. clicks but no turn, bad solenoid or not getting voltage from the battery to the big terminal
Found it!
The small wire on the starter was badly corroded under the insulation. After some searching, it's a common problem for 3's. There is even a TSB for it. I had a similar problem with my old 3, but it was the connector. So i cut and fit a new wire and spade connector, cleaned the terminal and it now starts! Woohoo!
Thanks for the help!
It only worked because you checked the the starter DEFIANTLY! 
